Locating intravascular images

ABSTRACT

The invention includes imaging catheters having image collectors co-located with radiopaque labels, methods of using the imaging catheters, and systems for locating the position of intravascular images within the body. In some instances, an angiogram is used to determine the precise location of the co-located radiopaque labels, and thus, the position of the intravascular image.

RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application No. 61/740,220, filed Dec. 20, 2012, which is incorporated by reference herein in its entirety.

TECHNICAL FIELD

The invention provides devices, methods, and systems for locating the position of an intravascular image within the body.

BACKGROUND

Intravascular imaging and endovascular surgery have increased the life expectancy and quality of life for patients suffering from cardiovascular disease. Imaging techniques such as intravascular ultrasound (IVUS), intravascular Doppler, and intravascular optical coherence tomography (OCT) allow radiologists, neurologists, neurosurgeons, cardiologists, vascular surgeons, etc., to directly visualize a patient's vasculature to observe occlusions, thrombi, embolisms, aneurisms, etc. Coupling the imaging techniques with advanced surgical procedures, it is possible to counteract cardiovascular disease by removing thrombi or placing stents in weakened vessels. Using such procedures, a patient at high risk for cardiac arrest can have the risk lessened, and experience a better quality of life after treatment. Furthermore, because intravascular imaging and endovascular surgery are less invasive than techniques such as coronary bypass, the risk of surgical complication is greatly reduced and hospital stays and recovery times are shortened.

While the procedures are non-invasive, the substantial distance between the entry into the body and the targeted tissue makes the procedures complex. Vascular access for an imaging catheter is gained through an arterial entry point such as the radial, brachial, or femoral artery. From the entry point, a provider can access the vasculature of most important organs (heart, lungs, kidneys, brain) by guiding the catheter along a placed guide wire to a feature of interest. Because there is some amount of travel between the entry point and the target, an additional imaging technique, such as angiography, is needed to determine the approximate position of the guide wire and/or catheter within the body.

Because the two imaging systems (intravascular imaging and angiography) are operated independently, it can be difficult to precisely locate imaged intravascular tissues within the body. A cardiologist will typically place a guide wire in the vasculature while observing the angiogram, moving the guide wire so that the distal end of the guide wire is approximately adjacent to a feature of interest. Once the guide wire is placed, the cardiologist will deliver the imaging catheter by pushing the catheter to a stop at the distal end of the guide wire. Logically, the subsequent tissue images, e.g., IVUS images, must be approximately located at the distal end of the guide wire, which was visualized previously using the angiogram. In some cases, when the location of the image is unclear, additional contrast and x-ray imaging are used to locate the catheter, which shows up in the angiogram as a pattern of shadows.

In many cases, the exact location of a tissue image within a body is not known, however, because the imaging plane of the image collector (e.g., ultrasound collector) is not well defined with respect to the distal end of the guide wire. This problem is especially acute when using advanced pullback imaging catheters that can be move longitudinally within the catheter once deployed. Because the image collector is very small, the shadow of the guide wire can make it difficult to locate the precise position of the image collector within the sensor package during translation. Furthermore, if a feature of concern is found while translating the image collector, it can be difficult to pinpoint the location of the feature without stopping the translation and adding additional contrast and x-rays. Unfortunately, angiography presents risks to both the patient and the provider. Angiography uses radiopaque contrast agents and x-ray imaging, e.g., fluoroscopy, to image the vasculature. Because the images are taken in real time, substantially greater amounts of x-ray radiation are required as compared to a radiograph (x-ray picture). In addition to the x-ray exposure, patients may suffer side effects from the radiopaque contrast agents, including pain, adverse drug interactions, and renal failure. For technicians and physicians, there are also risks of x-ray exposure as well as orthopedic injuries (e.g., lower back strain) due to the extra weight of the lead-lined aprons and other protective equipment.

Thus, there is a need for improved methods of locating an image produced by an image catheter during a procedure. Any improvement that decreases the time of a procedure using angiography will benefit both doctor and patient.

SUMMARY

The invention provides imaging catheters, methods, and systems that will benefit both the patient and technician/physician by making the precise location of an intravascular image easier to identify in an accompanying angiogram. By co-locating a radiopaque label with the image collector of an imaging catheter, it is easier to identify the exact location of the image collector and to correlate a given image with a specific location within the vasculature. The improvement in the image collector makes possible systems that can simultaneously display an intravascular image and pinpoint the location of that image on a corresponding angiogram. Imaging catheters of the invention are not limited to only having a radiopaque label at the image collector, however, as additional radiopaque markers may be used to facilitate identification of a distal tip or a pull-back cable.

In one aspect, the invention is an imaging catheter including a radiopaque label co-located with the image collector. The image collector can be a piezoelectric sensor, a micromachined transducer, a photodiode, a charge coupled device, a microchannel array, a lens, or an optical fiber. The catheter can be used to collect intravascular ultrasound (IVUS), intravascular optical coherence tomography (OCT), intravascular Doppler, or intravascular visible images. Because the radiopaque label does not transmit medical x-rays, it shows up as a dark spot in a fluoroscopic image of the subject, allowing a physician to quickly identify the location of an intravascular image obtained with the collector.

In another aspect, the invention is a method for locating the position of an intravascular image in a subject. The method includes inserting an intravenous imaging catheter having a radiopaque label co-located with an image collector into a subject and imaging a portion of the vasculature of the subject using the image collector. During or after the imaging, the area of the body of the patient where the catheter is located is imaged to determine the precise location of the radiopaque label and thus the location of the intravascular image is also known.

In another aspect, the invention is a system for locating the position of an intravascular image in a subject. The system includes a processor and a computer readable storage medium having instructions that when executed cause the processor to execute the methods of the invention. For example, the instructions may cause the processor to receive imaging data of vasculature of a subject collected with an image collector co-located with a radiopaque label and then subsequently receive an image (e.g., an angiogram) of the subject including the radiopaque label. Once the radiopaque label has been located in the image of the subject, the system outputs an image of the subject showing the location of the image collector and outputs an intravascular image of the vasculature of a subject. In some instances, the processor will output an image that simultaneously shows the location of the image collector and the vasculature of the subject. The system may additionally include the tools needed to obtain and process the imaging data and images, such as catheters, fluoroscopes, and related control equipment.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A shows a catheter for taking intravascular images having a radiopaque label co-located with the image collector;

FIG. 1B shows the detail of the collector assembly, including a radiopaque label co-located with the image collector;

FIG. 2 depicts an optical coherence tomography (OCT) imaging engine and patient interface module (PIM) having an imaging catheter including a marker co-located with an imaging element. The OCT system may include additional markers to show, e.g., the location of the pullback shaft or the location of the distal tip of the catheter;

FIG. 3 depicts the OCT imaging engine of FIG. 2 in greater detail;

FIG. 4 depicts an optical mixing setup for OCT image acquisition and processing;

FIG. 5 is a simultaneous display of an intravascular ultrasound (IVUS) image and an angiogram of the artery from which the IVUS image originated;

FIG. 6 is an alternative simultaneous display of an IVUS image and an angiogram of the artery from which the IVUS image originated;

FIG. 7 is a simultaneous display of an optical coherence tomography (OCT) image and an angiogram of the artery from which the OCT image originated;

FIG. 8 is a flowchart of a system of the invention;

FIG. 9 is block diagram of a system of the invention for locating the position of an intravascular image relative to an image of the vasculature of the subject;

FIG. 10 is a block diagram of a networked system for locating the position of an intravascular image relative to an image of the vasculature of the subject.

DETAILED DESCRIPTION

Using the image collectors with radiopaque labels and the systems and method described herein, physicians and other users of intravascular imaging will be able to precisely locate the position of a given intravascular image within the vasculature. The inventions will speed intravascular imaging procedures, and result in less contrast and x-ray exposure for patients. The inventions will also make it easier for users to locate tissues of interest, e.g., thrombi, for accompanying endovascular procedures.

Any targeted tissue can be imaged using methods and systems of the invention. In certain embodiments, systems and methods of the invention image within a lumen of a subject. Various lumen of biological structures may be imaged including, but not limited to, blood vessels, vasculature of the lymphatic and nervous systems, various structures of the gastrointestinal tract including lumen of the small intestine, large intestine, stomach, esophagus, colon, pancreatic duct, bile duct, hepatic duct, lumen of the reproductive tract including the vas deferens, uterus and fallopian tubes, structures of the urinary tract including urinary collecting ducts, renal tubules, ureter, and bladder, and structures of the head and neck and pulmonary system including sinuses, parotid, trachea, bronchi, and lungs.

Any vascular imaging system may be used with the devices, systems, and methods of the invention including, for example, ultrasound (IVUS), Doppler, and optical coherence tomography (OCT). Devices, methods, and systems using the invention can also be used for intravascular visible imaging by co-locating a radiopaque label with a visible image collector, such as with an optical fiber or a CCD array camera. By co-locating a radiopaque label with the image collector, it is possible to track the location of the image collector, and thus, the image plane of the measurement. The radiopaque label will typically be quite small (1-5 mm) and constructed from a metal that does not transmit medical x-rays, such as platinum, palladium, rhenium, tungsten, tantalum, or combinations thereof.

Catheters

In certain embodiments, the invention provides systems and methods for imaging tissue using intravascular ultrasound (IVUS). IVUS uses a catheter with an ultrasound probe attached at the distal end. The proximal end of the catheter is attached to computerized ultrasound equipment. To visualize a vessel via IVUS, angiography is used while a technician/physician positions the tip of a guide wire. The physician steers the guide wire from outside the body, through angiography catheters and into the blood vessel branch to be imaged.

An exemplary IVUS catheter is shown in FIGS. 1A-1B. Rotational imaging catheter 100 is typically around 150 cm in total length can be used to image a variety of vasculature, such as coronary or carotid arteries and veins. When the rotational imaging catheter 100 is used, it is inserted into an artery along a guide wire (not shown) to the desired location. Typically a portion of catheter, including a distal tip 110, comprises a lumen (not shown) that mates with the guide wire, allowing the catheter to be deployed by pushing it along the guide wire to its destination.

An imaging assembly 120 proximal to the distal tip 110, includes transducers 122 that image the tissue with ultrasound energy (e.g., 20-50 MHz range) and image collectors 124 that collect the returned energy (echo) to create an intravascular image. The imaging assembly 120 is shown in greater detail in FIG. 1B.

As shown in FIGS. 1A-1B, the imaging assembly 120 comprises transducers 122, image collectors 124, a radiopaque marker 125, a unibody 126, and a wiring bundle 128. The imaging assembly 120 is configured to rotate and travel longitudinally within imaging window allowing the imaging assembly 120 to obtain 360° images of vasculature over the distance of travel. The imaging assembly is rotated and manipulated longitudinally by a drive cable (not shown) attached to inner member 135. The drive cable may additionally include one or more radiopaque markers to facilitate locating the extent of the drive cable during a procedure. In some embodiments of rotational imaging catheter 100, the imaging window can be over 15 cm long, and the imaging assembly 120 can rotate and travel most of this distance, thus providing thousands of images along the travel. Because of this extended length of travel, it is especially useful to have radiopaque marker 125 co-located with image collector 124. That is, once the imaging assembly 120 has been pulled back a substantial distance from the tip of the catheter, radiopaque marker 125 allows a user to quickly verify the position of a given image rather than having to estimate with respect to the tip of the guide wire. In order to make locating an image easier, imaging window also has radiopaque markers 137 spaced apart at 1 cm intervals. Catheter 100 may also include a radiopaque marker at the distal tip to aid in visualization.

Rotational imaging catheter 100 additionally includes a hypotube 140 connecting the imaging window and the imaging assembly 120 to the ex-corporal portions of the catheter. The hypotube 140 combines longitudinal stiffness with axial flexibility, thereby allowing a user to easily feed the catheter 100 along a guide wire and around tortuous curves and branching within the vasculature. The ex-corporal portion of the hypotube includes shaft markers that indicate the maximum insertion lengths for the brachial or femoral arteries. The ex-corporal portion of catheter 100 also include a transition shaft 150 coupled to a coupling 160 that defines the external telescope section 165. The external telescope section 165 corresponds to the pullback travel, which is on the order of 130 mm. The end of the telescope section is defined by the connector 170 which allows the catheter 100 to be interfaced to a patient interface module (PIM) which includes electrical connections to supply the power to the transducer and to receive images from the image collector. The connector 170 also includes mechanical connections to rotate the imaging assembly 120. When used clinically, pullback of the imaging assembly is also automated with a calibrated pullback device (not shown) which operates between coupling 160 and connector 170. The imaging assembly can be a phased array IVUS imaging assembly, an pull-back type IVUS imaging assembly, or an IVUS imaging assembly that uses photoacoustic materials to produce diagnostic ultrasound and/or receive reflected ultrasound for diagnostics. IVUS imaging assemblies and processing of IVUS data are described for example in Yock, U.S. Pat. Nos. 4,794,931, 5,000,185, and 5,313,949; Sieben et al., U.S. Pat. Nos. 5,243,988, and 5,353,798; Crowley et al., U.S. Pat. No. 4,951,677; Pomeranz, U.S. Pat. No. 5,095,911, Griffith et al., U.S. Pat. No. 4,841,977, Maroney et al., U.S. Pat. No. 5,373,849, Born et al., U.S. Pat. No. 5,176,141, Lancee et al., U.S. Pat. No. 5,240,003, Lancee et al., U.S. Pat. No. 5,375,602, Gardineer et al., U.S. Pat. No. 5,373,845, Seward et al., Mayo Clinic Proceedings 71(7):629-635 (1996), Packer et al., Cardiostim Conference 833 (1994), “Ultrasound Cardioscopy,” Eur. J.C.P.E. 4(2):193 (June 1994), Eberle et al., U.S. Pat. No. 5,453,575, Eberle et al., U.S. Pat. No. 5,368,037, Eberle et at., U.S. Pat. No. 5,183,048, Eberle et al., U.S. Pat. No. 5,167,233, Eberle et at., U.S. Pat. No. 4,917,097, Eberle et at., and U.S. Pat. No. 5,135,486. All of these references are incorporated by reference herein.

The imaging assembly 120 produces ultrasound energy and receives echoes from which real time ultrasound images of a thin section of the blood vessel are produced. The transducers 122 are constructed from piezoelectric components that produce sound energy at 20-50 MHz. The image collector 124 comprises separate piezoelectric elements that receive the ultrasound energy that is reflected from the vasculature. Alternative embodiments of imaging assembly 120 may use the same piezoelectric components to produce and receive the ultrasonic energy, for example, by using pulsed ultrasound. Another alternative embodiment may incorporate ultrasound absorbing materials and ultrasound lenses to increase signal to noise.

The imaging assembly 120 used with the invention, including radiopaque marker 125, is not limited to ultrasound applications, however. Radiopaque marker 125 may be co-located with other image collectors, such as lenses, CCD arrays, and optical fibers, used with visible imaging, optical coherence tomography, or any other intravascular imaging system. Additionally, the radiopaque marker need not be disposed beneath, or interior to, the image collector. Alternative designs may have the radiopaque marker on top of, or external to, the image collector with windows or other openings that allow the image collector to function properly.

Regardless of the type of imaging, the radiopaque marker 125 will be co-located longitudinally with respect to the image collector to allow a user to identify the location of the collector. Accordingly, radiopaque marker 125 will be small in most instances, having a longitudinal dimension of less than 5 mm, e.g., less than 4 mm, e.g., less than 3 mm, e.g., less than 2 mm, e.g., less than 1 mm. The radiopaque marker 125 will be at least 0.2 mm, e.g., at least 0.3 mm, e.g., at least 0.4 mm, e.g., at least 0.5 mm. The radiopaque marker 125 may vary in axial size or diameter, depending upon its shape; however it will necessarily be small enough to fit within catheter 100. For example radiopaque marker 125 may have a diameter of at least 0.1 mm, e.g., at least 0.3 mm, e.g., at least 0.7 mm. The radiopaque marker 125 may be constructed from any material that does not transmit x-rays and has suitable mechanical properties, including platinum, palladium, rhenium, tungsten, and tantalum.

In other embodiments, the imaging catheter may be an Optical Coherence Tomography (OCT) catheter having an imaging element co-located with a radiopaque marker, or another suitable marker. OCT is a medical imaging methodology using a miniaturized near infrared light-emitting probe, and is capable of acquiring micrometer-resolution, three-dimensional images from within optical scattering media (e.g., biological tissue). OCT systems and methods are generally described in Castella et al., U.S. Pat. No. 8,108,030, Milner et al., U.S. Patent Application Publication No. 2011/0152771, Condit et al., U.S. Patent Application Publication No. 2010/0220334, Castella et al., U.S. Patent Application Publication No. 2009/0043191, Milner et al., U.S. Patent Application Publication No. 2008/0291463, and Kemp, N., U.S. Patent Application Publication No. 2008/0180683, the content of each of which is incorporated by reference in its entirety.

In OCT, a light source delivers a beam of light to an imaging device to image target tissue. Light sources can be broad spectrum light sources, or provide a more limited spectrum of wavelengths, e.g., near infra-red. The light sources may be pulsed or continuous wave. For example the light source may be a diode (e.g., superluminescent diode), or a diode array, a semiconductor laser, an ultrashort pulsed laser, or supercontinuum light source. Typically the light source is filtered and allows a user to select a wavelength of light to be amplified. Wavelengths commonly used in medical applications include near-infrared light, for example between about 800 nm and about 1700 nm.

Methods of the invention can be used in conjunction with imaging using any IVUS or OCT system, including OCT systems that operate in either the time domain or frequency (high definition) domain. In time-domain OCT, an interference spectrum is obtained by moving a scanning optic, such as a reference mirror, longitudinally to change the reference path and match multiple optical paths due to reflections of the light within the sample. The signal giving the reflectivity is sampled over time, and light traveling at a specific distance creates interference in the detector. Moving the scanning mechanism laterally (or rotationally) across the sample produces reflectance distributions of the sample (i.e., an imaging data set) from which two-dimensional and three-dimensional images can be produced.

In frequency domain OCT, a light source capable of emitting a range of optical frequencies passes through an interferometer, where the interferometer combines the light returned from a sample with a reference beam of light from the same source, and the intensity of the combined light is recorded as a function of optical frequency to form an interference spectrum. A Fourier transform of the interference spectrum provides the reflectance distribution along the depth within the sample.

Alternatively, in swept-source OCT, the interference spectrum is recorded by using a source with adjustable optical frequency, with the optical frequency of the source swept through a range of optical frequencies, and recording the interfered light intensity as a function of time during the sweep. An example of swept-source OCT is described in U.S. Pat. No. 5,321,501, incorporated by reference herein in its entirety.

Time- and frequency-domain systems can further vary based upon the optical layout of the systems: common beam path systems and differential beam path systems. A common beam path system sends all produced light through a single optical fiber to generate a reference signal and a sample signal whereas a differential beam path system splits the produced light such that a portion of the light is directed to the sample and the other portion is directed to a reference surface. Common beam path systems are described in U.S. Pat. No. 7,999,938; U.S. Pat. No. 7,995,210; and U.S. Pat. No. 7,787,127 and differential beam path systems are described in U.S. Pat. No. 7,783,337; U.S. Pat. No. 6,134,003; and U.S. Pat. No. 6,421,164, the contents of each of which are incorporated by reference herein in their entireties.

In certain embodiments, the invention provides a differential beam path OCT system with intravascular imaging capability as illustrated in FIG. 2. For intravascular imaging, a light beam is delivered to the vessel lumen via a fiber-optic based imaging catheter 826. The imaging catheter is connected through hardware to software on a host workstation. The hardware includes imagining engine 859 and a handheld patient interface module (PIM) 839 that includes user controls. The proximal end of imaging catheter 826 is connected to PIM 839, which is connected to imaging engine 859 as shown in FIG. 2.

An embodiment of imaging engine 859 is shown in FIG. 3. Imaging engine 859 (i.e., the bedside unit) houses power distribution board 849, light source 827, interferometer 831, and variable delay line 835 as well as a data acquisition (DAQ) board 855 and optical controller board (OCB) 851. PIM cable 841 connects imagining engine 859 to PIM 839 and engine cable 845 connects imaging engine 859 to the host workstation (not shown).

FIG. 4 shows an exemplary light path in a differential beam path system which may be used in an OCT system suitable for use with the invention. Light for producing the measurements originates within light source 827. This light is split between main OCT interferometer 905 and auxiliary interferometer 911. In some embodiments, the auxiliary interferometer is referred to as a “clock” interferometer. Light directed to main OCT interferometer 905 is further split by splitter 917 and recombined by splitter 919 with an asymmetric split ratio. The majority of the light from splitter 917 is guided into sample path 913 while the remainder goes into reference path 915. Sample path 917 includes optical fibers running through PIM 839 and imaging catheter core 826 and terminating at the distal end of the imaging catheter, where the sample is measured.

The reflected light is transmitted along sample path 913 to be recombined with the light from reference path 915 at splitter 919. A variable delay line (VDL) 925 on the reference path uses an adjustable fiber coil to match the length of reference path 915 to the length of sample path 913. The reference path length is adjusted by a stepper motor translating a mirror on a translation stage under the control of firmware or software.

The combined light from splitter 919 is split into orthogonal polarization states, resulting in RF-band polarization-diverse temporal interference fringe signals. The interference fringe signals are converted to photocurrents using PIN photodiodes 929 a, and 929 b, on optical controller board (OCB) 851. The interfering, polarization splitting, and detection steps are done by a polarization diversity module (PDM) (not shown) on OCB 851. Signal from OCB 851 is sent to DAQ 855, shown in FIG. 3. DAQ 855 includes a digital signal processing (DSP) microprocessor and a field programmable gate array (FPGA) to digitize signals and communicate with the host workstation and PIM 839. The FPGA converts raw optical interference signals into meaningful reflectivity measurements. DAQ 855 also compresses data as necessary to reduce image transfer bandwidth, e.g., to 1 Gbps, e.g., by compressing frames with a glossy compression JPEG encoder.

Rotational imaging catheter 100 can be used to obtain IVUS images such as shown in FIGS. 5-6, however it is understood that similar images may be generated with OCT, as discussed above, to generate OCT images, such as shown in FIG. 7. FIG. 5 (left hand side) shows an intravascular ultrasound image of a pulmonary artery, prior to placement of a stent. The border lines define the interior diameter of the lumen (blood vessel) and the shadow of the catheter. The shadow of the catheter serves as a calibration for luminal diameter. In other words, the ratio between the imaged area and the catheter shadow area can be used to calculate the actual luminal area at the point of imaging. However, while the absolute luminal area can be calculated from the intravascular image, the actual location of the luminal image is not evident from the intravascular image.

Accordingly, it is necessary to use a secondary imaging system, such as angiography, to determine the location of the image collector, and thus the acquired image. As discussed above, angiography uses a combination of x-ray imaging, typically fluoroscopy, and injected radiopaque contrasts to identify the structure of the vasculature. The real time image of the vasculature is typically displayed on a monitor during the intravascular procedure so that the technician or physician can watch the manipulation of the guide wire or catheter in real time. The angiogram may be processed with software and displayed on a computer, or the image may be a closed circuit image of a scintillating surface combined with a visibly fluorescent material. Newer fluoroscopes may use flat panel (array) detectors that are sensitive to lower doses of x-ray radiation and provide improved resolution over more traditional scintillating surfaces. An angiogram of a pulmonary artery is shown in the right hand image of FIG. 5.

Imaging Systems

Using the devices of the invention, i.e., catheters with radiopaque labels co-located with the image collectors, improved systems for locating the position of an intravascular image can be provided. In principle, the methods can be as simple as imaging a portion of the vasculature of the subject using the image collector, e.g., as part of an imaging catheter, imaging the subject to determine the location of the radiopaque label co-located with an image collector, e.g., using angiography, and locating the position of the intravascular image, based upon the position of the radiopaque label.

A simple display using the described method is shown in FIG. 5, where the white box indicates the location of the left-hand intravascular image as defined by locating the radiopaque label (not shown in angiogram). In some embodiments, image tagging software can be used to automatically identify the location of the radiopaque label which will appear as a small spot having a darker color than the rest of the image. The image tagging software can automatically locate a box corresponding to the position of the image collector on the angiograph, e.g., as shown in FIG. 5. A physician using such this system will be able to locate specific structures of interest and return to those structures with less effort. Accordingly, the procedure will take less time, and the patient and the physician will be exposed to less x-ray radiation.

In addition to the embodiments described above, the devices, methods, and systems of the invention can be used to catalogue and display overlapping images of intravascular imaging and vascular structure, as is shown in FIGS. 5 to 7. Again, using image tagging software, or other algorithms, it is possible to display an angiogram that co-displays intravascular images. FIG. 6 shows a simulated IVUS image co-located with the location of the IVUS image on an angiogram of pulmonary arteries. FIG. 7 shows an OCT image co-located with the location of the OCT image on an angiogram of pulmonary arteries. As discussed above, the principles of the invention using IVUS or OCT are identical once the radiopaque label has been co-located with the image collector.

In other embodiments, an angiogram, or more likely a simulated angiogram, can be used after the procedure to post-operatively examine the vasculature of the patient. Using the images of FIGS. 6 and 7, a technician or physician can later scroll over the angiogram and click on specific vasculature to examine the corresponding intravascular image. Accordingly, the methods and systems of the invention can provide a more complete picture of the cardiovascular health of the patient. Further improvements on the system could use automatic border detection and/or color labeling as described in U.S. Patent Publication No. 2008/0287795, incorporated herein by reference in its entirety.

A flowchart 200 of a system of the invention is shown in FIG. 8. At step 210 intravascular imaging data, such as from an imaging catheter having a radiopaque label co-located with the image collector, is received. At step 220 vasculature imaging data, such as from a fluoroscope, is received. At step 230 the vasculature imaging data is analyzed to determine if the radiopaque label is identifiable. If the label is not identifiable, the system receives new vasculature imaging data. If the label is identifiable, the system proceeds to output a vascular image, such as an angiogram, showing the location of the intravascular image. Then the system also outputs the intravascular image, e.g., an IVUS or OCT image. In some embodiments, the system simultaneously outputs both the angiogram and intravascular image in the same image (dashed box).

A system of the invention may be implemented in a number of formats. An embodiment of a system 300 of the invention is shown in FIG. 9. The core of the system 300 is a computer 360 or other computational arrangement (see FIG. 10) comprising a processor 365 and memory 367. The memory has instructions which when executed cause the processor to receive imaging data of vasculature of a subject collected with an image collector co-located with a radiopaque label. The imaging data of vasculature will typically originate from an intravascular imaging device 320, which is in electronic and/or mechanical communication with an imaging catheter 325. The memory additionally has instructions which when executed cause the processor to receive an image of the subject including the radiopaque label. The image of the subject will typically be an x-ray image, such as produced during an angiogram or CT scan. The image of the subject will typically originate in an x-ray imaging device 340, which is in electronic and/or mechanical communication with an x-ray source 343 and an x-ray image collector 347 such as a flat panel detector, discussed above. Having collected the images, the processor then processes the image, and outputs an image of the subject showing the location of the image collector, as well as an image of the vasculature of a subject. The images are typically output to a display 380 to be viewed by a physician or technician. In some embodiments a displayed image will simultaneously include both the intravascular image and the image of the vasculature, for example as shown in FIGS. 6 and 7.

In advanced embodiments, system 300 may comprise an imaging engine 370 which has advanced image processing features, such as image tagging, that allow the system 300 to more efficiently process and display combined intravascular and angiographic images. The imaging engine 370 may automatically highlight or otherwise denote areas of interest in the vasculature. The imaging engine 370 may also produce 3D renderings of the intravascular images and or angiographic images. In some embodiments, the imaging engine 370 may additionally include data acquisition functionalities (DAQ) 375, which allow the imaging engine 370 to receive the imaging data directly from the catheter 325 or collector 347 to be processed into images for display.

Other advanced embodiments use the I/O functionalities 362 of computer 360 to control the intravascular imaging 320 or the x-ray imaging 340. In these embodiments, computer 360 may cause the imaging assembly of catheter 325 to travel to a specific location, e.g., if the catheter 325 is a pull-back type. The computer 360 may also cause source 343 to irradiate the field to obtain a refreshed image of the vasculature, or to clear collector 347 of the most recent image. While not shown here, it is also possible that computer 360 may control a manipulator, e.g., a robotic manipulator, connected to catheter 325 to improve the placement of the catheter 325.

A system 400 of the invention may also be implemented across a number of independent platforms which communicate via a network 409, as shown in FIG. 10. Methods of the invention can be performed using software, hardware, firmware, hardwiring, or combinations of any of these. Features implementing functions can also be physically located at various positions, including being distributed such that portions of functions are implemented at different physical locations (e.g., imaging apparatus in one room and host workstation in another, or in separate buildings, for example, with wireless or wired connections).

As shown in FIG. 10, the intravascular imaging system 320 and the x-ray imaging system 340 are key for obtaining the data, however the actual implementation of the steps, for example the steps of FIG. 8, can be performed by multiple processors working in communication via the network 409, for example a local area network, a wireless network, or the internet. The components of system 400 may also be physically separated. For example, terminal 467 and display 380 may not be geographically located with the intravascular imaging system 320 and the x-ray imaging system 340.

As shown in FIG. 10, imaging engine 859 communicates with host workstation 433 as well as optionally server 413 over network 409. In some embodiments, an operator uses host workstation 433, computer 449, or terminal 467 to control system 400 or to receive images. An image may be displayed using an I/O 454, 437, or 471, which may include a monitor. Any I/O may include a monitor, keyboard, mouse or touch screen to communicate with any of processor 421, 459, 441, or 475, for example, to cause data to be stored in any tangible, nontransitory memory 463, 445, 479, or 429. Server 413 generally includes an interface module 425 to communicate over network 409 or write data to data file 417. Input from a user is received by a processor in an electronic device such as, for example, host workstation 433, server 413, or computer 449. In certain embodiments, host workstation 433 and imaging engine 855 are included in a bedside console unit to operate system 400.

In some embodiments, the system may render three dimensional imaging of the vasculature or the intravascular images. An electronic apparatus within the system (e.g., PC, dedicated hardware, or firmware) such as the host workstation 433 stores the three dimensional image in a tangible, non-transitory memory and renders an image of the 3D tissues on the display 380. In some embodiments, the 3D images will be coded for faster viewing. In certain embodiments, systems of the invention render a GUI with elements or controls to allow an operator to interact with three dimensional data set as a three dimensional view. For example, an operator may cause a video affect to be viewed in, for example, a tomographic view, creating a visual effect of travelling through a lumen of vessel (i.e., a dynamic progress view). In other embodiments an operator may select points from within one of the images or the three dimensional data set by choosing start and stop points while a dynamic progress view is displayed in display. In other embodiments, a user may cause an imaging catheter to be relocated to a new position in the body by interacting with the image.

In some embodiments, a user interacts with a visual interface and puts in parameters or makes a selection. Input from a user (e.g., parameters or a selection) are received by a processor in an electronic device such as, for example, host workstation 433, server 413, or computer 449. The selection can be rendered into a visible display. In some embodiments, an operator uses host workstation 433, computer 449, or terminal 467 to control system 400 or to receive images. An image may be displayed using an I/O 454, 437, or 471, which may include a monitor. Any I/O may include a keyboard, mouse or touch screen to communicate with any of processor 421, 459, 441, or 475, for example, to cause data to be stored in any tangible, nontransitory memory 463, 445, 479, or 429. Server 413 generally includes an interface module 425 to effectuate communication over network 409 or write data to data file 417. Methods of the invention can be performed using software, hardware, firmware, hardwiring, or combinations of any of these. Features implementing functions can also be physically located at various positions, including being distributed such that portions of functions are implemented at different physical locations (e.g., imaging apparatus in one room and host workstation in another, or in separate buildings, for example, with wireless or wired connections). In certain embodiments, host workstation 433 and imaging engine 855 are included in a bedside console unit to operate system 400.

Processors suitable for the execution of computer program include, by way of example, both general and special purpose microprocessors, and any one or more processor of any kind of digital computer. Generally, a processor will receive instructions and data from a read-only memory or a random access memory or both. The essential elements of computer are a processor for executing instructions and one or more memory devices for storing instructions and data. Generally, a computer will also include, or be operatively coupled to receive data from or transfer data to, or both, one or more mass storage devices for storing data, e.g., magnetic, magneto-optical disks, or optical disks. Information carriers suitable for embodying computer program instructions and data include all forms of non-volatile memory, including by way of example semiconductor memory devices, (e.g., EPROM, EEPROM, NAND-based flash memory, solid state drive (SSD), and other flash memory devices); magnetic disks, (e.g., internal hard disks or removable disks); magneto-optical disks; and optical disks (e.g., CD and DVD disks). The processor and the memory can be supplemented by, or incorporated in, special purpose logic circuitry.

To provide for interaction with a user, the subject matter described herein can be implemented on a computer having an I/O device, e.g., a CRT, LCD, LED, or projection device for displaying information to the user and an input or output device such as a keyboard and a pointing device, (e.g., a mouse or a trackball), by which the user can provide input to the computer. Other kinds of devices can be used to provide for interaction with a user as well. For example, feedback provided to the user can be any form of sensory feedback, (e.g., visual feedback, auditory feedback, or tactile feedback), and input from the user can be received in any form, including acoustic, speech, or tactile input.

The subject matter described herein can be implemented in a computing system that includes a back-end component (e.g., a data server 413), a middleware component (e.g., an application server), or a front-end component (e.g., a client computer 449 having a graphical user interface 454 or a web browser through which a user can interact with an implementation of the subject matter described herein), or any combination of such back-end, middleware, and front-end components. The components of the system can be interconnected through network 409 by any form or medium of digital data communication, e.g., a communication network. Examples of communication networks include cell networks (3G, 4G), a local area network (LAN), and a wide area network (WAN), e.g., the Internet.

The subject matter described herein can be implemented as one or more computer program products, such as one or more computer programs tangibly embodied in an information carrier (e.g., in a non-transitory computer-readable medium) for execution by, or to control the operation of, data processing apparatus (e.g., a programmable processor, a computer, or multiple computers). A computer program (also known as a program, software, software application, app, macro, or code) can be written in any form of programming language, including compiled or interpreted languages (e.g., C, C++, Perl), and it can be deployed in any form, including as a stand-alone program or as a module, component, subroutine, or other unit suitable for use in a computing environment. Systems and methods of the invention can include programming language known in the art, including, without limitation, C, C++, Perl, Java, ActiveX, HTML5, Visual Basic, or JavaScript.

A computer program does not necessarily correspond to a file. A program can be stored in a portion of file 417 that holds other programs or data, in a single file dedicated to the program in question, or in multiple coordinated files (e.g., files that store one or more modules, sub-programs, or portions of code). A computer program can be deployed to be executed on one computer or on multiple computers at one site or distributed across multiple sites and interconnected by a communication network.

A file can be a digital file, for example, stored on a hard drive, SSD, CD, or other tangible, non-transitory medium. A file can be sent from one device to another over network 409 (e.g., as packets being sent from a server to a client, for example, through a Network Interface Card, modem, wireless card, or similar).

Writing a file according to the invention involves transforming a tangible, non-transitory computer-readable medium, for example, by adding, removing, or rearranging particles (e.g., with a net charge or dipole moment) into patterns of magnetization by read/write heads, the patterns then representing new collocations of information desired by, and useful to, the user. In some embodiments, writing involves a physical transformation of material in tangible, non-transitory computer readable media with certain properties so that optical read/write devices can then read the new and useful collocation of information (e.g., burning a CD-ROM). In some embodiments, writing a file includes using flash memory such as NAND flash memory and storing information in an array of memory cells include floating-gate transistors. Methods of writing a file are well-known in the art and, for example, can be invoked automatically by a program or by a save command from software or a write command from a programming language.

In certain embodiments, display 380 is rendered within a computer operating system environment, such as Windows, Mac OS, or Linux or within a display or GUI of a specialized system. Display 380 can include any standard controls associated with a display (e.g., within a windowing environment) including minimize and close buttons, scroll bars, menus, and window resizing controls. Elements of display 380 can be provided by an operating system, windows environment, application programming interface (API), web browser, program, or combination thereof (for example, in some embodiments a computer includes an operating system in which an independent program such as a web browser runs and the independent program supplies one or more of an API to render elements of a GUI). Display 380 can further include any controls or information related to viewing images (e.g., zoom, color controls, brightness/contrast) or handling files comprising three-dimensional image data (e.g., open, save, close, select, cut, delete, etc.). Further, display 380 can include controls (e.g., buttons, sliders, tabs, switches) related to operating a three dimensional image capture system (e.g., go, stop, pause, power up, power down).

In certain embodiments, display 380 includes controls related to three dimensional imaging systems that are operable with different imaging modalities. For example, display 380 may include start, stop, zoom, save, etc., buttons, and be rendered by a computer program that interoperates with IVUS, OCT, or angiogram modalities. Thus display 380 can display an image derived from a three-dimensional data set with or without regard to the imaging mode of the system.

INCORPORATION BY REFERENCE

References and citations to other documents, such as patents, patent applications, patent publications, journals, books, papers, web contents, have been made throughout this disclosure. All such documents are hereby incorporated herein by reference in their entirety for all purposes.

EQUIVALENTS

Various modifications of the invention and many further embodiments thereof, in addition to those shown and described herein, will become apparent to those skilled in the art from the full contents of this document, including references to the scientific and patent literature cited herein. The subject matter herein contains important information, exemplification and guidance that can be adapted to the practice of this invention in its various embodiments and equivalents thereof. 

The invention claimed is:
 1. An imaging catheter comprising: a flexible elongate member including a proximal portion and a distal portion sized and shaped for positioning within a vessel of a patient; an imaging assembly disposed at the distal portion of the flexible elongate member, the imaging assembly including: an image collector; a body member centrally disposed with respect to the image collector; and a radiopaque label centrally disposed with respect to the image collector, wherein the radiopaque label is co-located longitudinally in the imaging catheter with respect to the image collector in a fixed manner such that the radiopaque label and the image collector remain co-located longitudinally while at least the imaging assembly is moved within the vessel; and an inner member extending longitudinally through the body member, wherein the imaging assembly is slidably coupled to the inner member and further configured to travel longitudinally with respect to the inner member such that the imaging assembly is capable of being translated while imaging vasculature.
 2. The imaging catheter of claim 1, wherein the image collector is a piezoelectric sensor, a micromachined transducer, a photodiode, a charge coupled device, a microchannel array, or a lens.
 3. The imaging catheter of claim 2, wherein the imaging catheter is an intravascular ultrasound imaging probe.
 4. The imaging catheter of claim 2, wherein the imaging catheter is an intravascular optical coherence tomography imaging probe.
 5. The imaging catheter of claim 1, wherein the radiopaque label is less than 3 mm in length measured longitudinally along the catheter.
 6. The imaging catheter of claim 1, wherein the radiopaque label comprises platinum, palladium, rhenium, tungsten, or tantalum.
 7. A method of locating the position of an intravascular image in a subject, comprising: inserting, into a subject, an intravascular imaging catheter comprising an imaging assembly, the imaging assembly comprising: an image collector; a body member centrally disposed with respect to the image collector; an inner member extending longitudinally through the body member; and a radiopaque label centrally disposed with respect to the image collector, wherein the radiopaque label is co-located longitudinally in the intravascular imaging catheter with respect to the image collector in a fixed manner such that the radiopaque label and the image collector remain co-located longitudinally while the catheter is moved within vasculature of the subject relative to the inner member; imaging a portion of the vasculature of the subject using the image collector; imaging the subject to determine the location of the radiopaque label; and locating the position of the intravascular image, based upon the position of the radiopaque label.
 8. The method of claim 7, wherein imaging the subject comprises obtaining an x-ray image of the subject.
 9. The method of claim 8, wherein the x-ray image is obtained with fluoroscopy or x-ray computed tomography (CT scanning).
 10. The method of claim 7, further comprising displaying an image of the subject including the radiopaque label.
 11. The method of claim 7, wherein the intravascular imaging step comprises ultrasound imaging or optical coherence tomography (OCT) imaging.
 12. A system for locating the position of an intravascular image in a subject, comprising: an imaging catheter comprising: an imaging assembly disposed at the distal portion of a flexible elongate member, the imaging assembly including: an image collector; a body member centrally disposed with respect to the image collector; an inner member extending longitudinally through the body member; and a radiopaque label centrally disposed with respect to the image collector, wherein the image collector is co-located longitudinally in an imaging catheter with respect to the radiopaque label in a fixed manner such that the radiopaque label and the image collector remain co-located while the catheter is moved within vasculature of the subject relative to the inner member; a processor; and a computer readable, non-transitory storage medium having instructions that when executed cause the processor to: receive imaging data of the vasculature of a subject collected with the image collector; receive an x-ray image of the subject including the radiopaque label; output an image of the subject showing the location of the image collector using the x-ray image of the subject including the radiopaque label; and output an image of the vasculature of a subject at the location of the image collector.
 13. The system of claim 12, wherein the computer readable, non-transitory storage medium has instructions that when executed cause the processor to output an image simultaneously showing the location of the image collector and the vasculature of the subject.
 14. The system of claim 12, wherein the image collector is a piezoelectric sensor, a micromachined transducer, a photodiode, a charge coupled device, a microchannel array, or a lens. 